How Poisonous, How Harmful?

Ingestion causes vomiting, diarrhoea, epigastric pain, acute
gastroenteritis hepatic and renal impairment. Seizures may be
observed. Death can occur due to liver failure. In women, uterine
haemorrhage and abortion may occur. But there is nothing about the
plant which encourages ingestion.

The burn caused by exposure
to sun
after
rubbing rue onto
the skin

Dermatitis due to photosensitization results from contact with
the furocoumarins. There is some dispute as to how that contact can
be achieved. There are those who say that simply being near a
rue may cause photosensitization but most of the recorded incidents
relate to rue being rubbed onto the skin causing the plant material
to break down and release its furocoumarins.

My own experience accords with the view that the plant material
must be damaged to release its ingredients. Brushing my hand
through a clump of the growing plant produced no ill effects which
accords with the gardeners' experience of never wearing gloves when
working with rue, but scrunching up some leaves and rubbing them on
a small area of the back of the hand resulted in a slightly painful
burn appearing a couple of days later. But, see under 'Incidents'.

Sources - The Internet

It is often said that the Internet is a very useful tool.
Well, a chainsaw is a very useful tool but it can be enormous
harmful if it isn’t used properly. Though my initial research, in
2003/4, was mostly done on the Internet, it soon became clear that
many pages which claimed to be definitive were far from it.

As a result I began investing in the books which were often cited as
the source of the information presented and now have an extensive
library including most of the most famous ‘herbals’ from the last
2000 years and more.

But, the Internet remains a useful tool, especially for looking into
the stories offered as fact by visitors to the Alnwick Garden Poison
Garden.

Where information from websites is used on this site it is always
the result of researching more than one site and comparing the
‘facts’ presented.

Incidents

A professional gardener was weeding between a number of rue
plants with bare arms and hands, as she had done many times before.
No damage was done to the rue itself. The next day was especially
sunny and by the afternoon her inner arms and parts of the backs of
her hands were red and sore. Blistering then occurred and took a
number of weeks to heal. It may be that the significant factor was
the very bright sun on the day after contact. It could also be that
the plants had produced an unusually large concentration of
furocoumarins that season. See the
Heracleum mantegazzianum, giant hogweed, page for the possible
explanation.

This particular incident suggests that the effects of contact
with the intact plant are unpredictable making it, if anything,
more of a problem than one whose effects are consistent. In
2017, I was told of another incident where working close to rue
had produced severe blistering.

A two year old boy was reported to have suffered burns after
simply playing near a rue bush. The fact that the burns were
confined to his fingers and around his mouth suggests that he may
have been crushing the leaves and mouthing them as young children
do.

Almost all reported incidents centre around the use of rue as a
mosquito repellent. Burns are, often, seen in striations around the
neck.

A case was reported in 1999 where Ruta graveolens caused skin
problems for someone who had applied it to safeguard themselves
from 'evil spirits'.

Folklore and Facts

In folklore, it was used to keep various unpleasant things out of
the house. It was hung in doors and windows to prevent evil spirits
from entering the house and worn on the belt to keep witches away.

Juice from a crushed stem spread on a wall around a doorway or
window frame would keep fleas out of the house. It may be that this
belief led to the idea that rue could be used as a mosquito
repellent. There are, certainly, a number of internet sites
offering repellent creams said to contain essence of rue and a few
other sites even go so far as to suggest rubbing the plant itself
onto children.

John Gerard says that burning rue will keep serpents away, this
use being confirmed by the fact that a weasel will eat rue before it
fights a serpent.